The Court of Arbitration of Sport will begin appeal hearings on January 22 for 39 Russian athletes banned for life from the Olympics because of alleged doping at the 2014 Sochi Winter Games.

Two witnesses who played key roles in getting Russia banned from the Olympics, whistle-blower Grigory Rodchenkov and World Anti-Doping Agency investigator Richard McLaren, will testify by video at the closed-door hearings, the court said in a statement.

The court said the combined hearings should last for six days at a conference center in Geneva.

One panel of three judges will hear 28 cases and a second panel will judge 11. Two of the judges -- Christoph Vedder and Dirk-Reiner Martens, both from Germany -- will sit on both three-person panels, the court said.

Verdicts are expected by February 2, one week before the Pyeongchang Winter Olympics are due to begin in South Korea.

A further three appeal cases in biathlon disciplines will not be heard next week, the court said.

The International Olympic Committee recently imposed lifetime bans on 43 Russians for doping. Maxim Belugin, a member of bobsleigh teams which finished in fourth place at Sochi in 2014, is the only banned athlete not to have lodged an appeal with the court.

The 42 athletes who appealed deny being part of a state-backed doping program that Olympics authorities said was in place during the Sochi Olympics. All of the athletes were retroactively disqualified from the Sochi games over the doping allegations.

The first group of athletes whose hearings have been combined are in bobsled, cross-country skiing, skeleton, and speed skating. They include athletes who have continued to compete in World Cup races not controlled by the International Olympic Committee.

The second group of 11 cases is concerns bobsled, luge, and women's ice-hockey events.